Abstract
This paper focuses upon the optimal repair and inspection policies of public facilities under uncertainty. The deterioration processes of the facilities are supposed to be partially observable by inspection. The optimal impulse control problem is formulated to find out the optimal timming for ispection and repairing so as to minimize the expected life cycle costs. The state dependent rules are presented to determine the optimal timing for inspection and reparing based upon the observation of deterioration levels. The paper is concluded by illustrating numerical examples.